Process for reclaiming used lubricating and insulating oils



Patented Mar.v 6, 1928.

I UNITED STATES PATENT OFFICE.-

ARGHIBALD F. MESTON, OF POUGHKEEPSIE, NEW YORK, ASSIGNOR TO THE DE LAVAL SEPARATOR COMPANY, OF NEW YORK, N. Y., A CORPORATION OF NEW JERSEY.

PROCESS FOR RECLAIMING USED LUBRICATING AND IITSULATING 0118.

No Drawing. Application filed larch 23, 1925. Serialli'o. 17,801.

The object of my invention is to provide with such clarifying and purifying agents a process for purifying used lubricating in other known ways (as by percolation) and insulating 0118, especially turbine, transthan by passing the mixture through a cenformer and switch oils. These oils ordinaritrifuge; but removal of such a ent by cenly contain finely divided solid carbon, water, trifugation presents distinct a vantages in sludge and organic acids. I will describe the present process. one method of carryin out the process that After many trials with various neutraliz- I have applied success ully to the treatment ing substances, I have found trisodium of dirty switch oil. phosphate (Na PO,.12I-I,O) possesses propup The dirty oil should be heated to a temerties which make it especially applicable perature of from 150 F. to 200 F. (prefto petroleum oil purification. Petroleum oils erably from 170 F. --to-190 F.) and thorwhich have been in use, especially when exoughly mixed with a solution in water of posed to air and high temperatures, contain trisodium phosphate. I have found that 2 organic substances which have the prop- 15 to 5% by volume of a solution having a erties of acids. It is desirable when purifydensity about 10 Baum at 100 F. gives ing such oils to neutralize these acids. good results. A solution of this strength When a caustic solution is added to an oil is made by dissolving about 15 parts of the containing acids, a tight emulsion almost salt in 100 parts of water by weight. always results, considerable of the oil be- 20 After agitation, the oil should be cooled ing dispersed throughout the water solution slowly (2 hours or more) down to a temin very fine subdivision. I find, however, perature of 120 to 140 F. It will then that when trisodium phosphate is used, the be found that a large part of the water emulsion is resolved comparatively quickly solution, dirt, and soaps will settle to the by settling or centrifugin Another rea- 25 bottom and may. be drawn oif. The partison for using a solution of trisodium phosally cleaned oil should then be run through phate is that it acts as a detergent and is a centrifugal oil purifier (a machine of the effective in agglomerating the suspended type disclosed in the Snyder Patent No. carbon in switch oil and the like, causing it 1,283,343 is suitable for this process) to reto agglomerate and settle. A further ad- 30 move most of the remaining dirt, water and vantage is the fact that a solution of the soaps. strength needed is not difficult to handle,

The centrifuged oil is then thoroughly does not injure the hands except on long agitated with about one to four per cent of exposure, and is not costly. activated earth, allowed to settle for five to The principal advantage, however, of the 35 ten hours, to remove most of the earth, and trisodium' phosphate solution is that it is then passed through the same centrifugal as especially efiective in preparing the oil for before to remove the remaining earth, soap subsequent treatment with a purifying earth. 1 and moisture. The commonly known and used purifying A very efficient activated earth is made earths do not remove organic acids. If,

40 from montmorillonite (a kind of bentonite, however, the acids are neutralized by means found in central California) which is finely of an ordinary alkaline solution, the result ground, treated with a mineral acid refof such emulsion is liable to be a tight erably sulphuric acid) and dried. uch emulsion, as above stated. If the neutralearth has to a remarkable degree the propized oil contains any appreciable amount of 4.5 crty of removing moisture, coloring matter soaps or soapy water, a large amount of and other im urities from oils. One prepearth will be required, because none of the aration of suc earth is sold under the trade earth will act by polymerization or absorpname of Filtrol. Fullers earth and certion to remove coloring matter, or the like, tain other earths, which have this same propuntil all the soap and water have been taken so erty to a lesser degree, may be used, but care of. When, however, preparatory to the with less efficiency. In fact, any of the earth treatment, the oil is treated with triknown inert clarifying and purifying agents sodium phosphate, as described, the oil is for treating oil may be (less preferably) neutralized and prepared for the earth treatsubstituted for the activated earths specimerit without causing a ti ht emulsion.

55 fied. It is also possible to treat the oil Most of the soapy water, or tfie like, can be no removed by settling and centrifuging, leaving only a very small amount to be removed by the earth.

Some oils upon prolonged vigorous agitation with a trisodium phosphate solution, especially oils which contain much sludge and other impurities, make an emulsion which is not readily broken. In such cases, it is often advantageous to leave the trisodium phosphate solution in the oil for but a short time. By centrifugation, the phosphate solution, together with solid impurities, is separated from the oil. The oil and solution are separately discharged, a large part of the solids being retained in the bowl of the centrifuge. The trisodium phosphate solution is returned to the oil and agitated vigorously for the purpose of bringing about a more complete neutralization and for agglomerating or salting out the soaps formed. If the trisodium phosphate solution removed from the oil by the centrifuge after the first wash is too weali for subsequent washing operations, it may be strengthened by the addition of more trisodium phosphate, or if it be so contaminated as to be unfit for re-use, new solution may be used. Following this treatment (preferably after cooling to 120-140 F.), the oil is again centrifuged. If examination after cooling discloses the fact that the oil has responded incompletely to the trisodium phosphate treatment, it may, because of the comparatively small content of impurities, be retreated and centrifuged without re-heating.

.An example of a switch oil that has been successfully treated by this process is one containing about 1% by volume of solid carbon and aving an acidity requiring .5 mg. of potassium hydroxid for neutralization of 1 gram of oil. The purified product is a beautifully brilliant oil having no sediment, having an acidity requiring .02 mg. of postassium hydroxid for neutralization, a demulsibility (Herschel) of 1620 and a R. E. value of 40 seconds. R. E. is a known abbreviation for resistance to emulsification, as indicated by the time required for gravity separation of an oil and water mixture under standard conditions, as specified by the American Society for Testing Materials.

What I claim is:

1. The process of purifying lubricating and insulating oils containing sludge, carbon, moisture and acid bodies, which comprises mixing the oil with a solution of trisodium phosphate, separating partially purified oil from the trisodinm phosphate solution, carbon, sludge and soaps, mixing the oil with more than one and less than four per cent activated earth, and centrifuging the oil to remove suspended earth and other impurities.

2. The process of reclaiming used oil, which comprises mixing the oil with a solu' tion of trisodium phosphate, centrifuging to remove the trisodium phosphate solution and agglomerated impurities, mixing the partially purified oil with more than one and less than four per cent of activated earth, and again centrifuging to remove earth, water and other impurities.

3. The process of reclaiming used oil, which comprises heating the oil to a tcm perature of from 150 F. to 200 F. and mixing same with a solution of trisodium phosphate, and subjecting the oil to a plurality of operations each of which comprises centrifuging to separate oil from the trisodinm phosphate solution and agglomerated impurities, and after one of said separating operations and before another of said separating operations cooling the oil to a temperature of from 120 F. to 140 F.

4. The process of reclaiming used oil, which comprises heating the oil to a temperature of from 150 F. to 200 F. and mixing with a solution of trisodium phosphate, subjecting the oil to a plurality of operations each of which comprises centrifuging to separate oil from the trisodium phosphate solution and agglomerated impurities, and after one and before another of said separating operations cooling the oil to a temperature of from 120 F. to 140 F. and then mixing the oil with more than one and less than four per cent activated earth and centrifuging the oil to remove suspended earth and impurities that have not been removed in the preceding operations.

5. The process of purifying lubricating and insulating oils containing sludge, carbon, moisture and acid bodies, which comprises mixing the oil with a solution of trisodium phosphate at a temperature between 150 and 200 F., centrifuging at such temperature to remove the trisodium phosphate solution, carbon, sludge and soaps that are not oil-soluble, mixing the oil with the same -.trisodium phosphate solution from which the carbon and sludge have been centrifugally removed, cooling to 120140 F., again centrifuging to remove the trisodium phosphate solution and additional soaps and impurities, and treating the oil with a clarifying and purifying agent.

In testimony of which invention, I have hereunto set my hand, at Ponghkeepsie, New York, on this sixteenth day of March,

ARGHIBALD F. MESTON. 

